LES and pimpleFoam: Is it wrong to do many Pimple/inner Loops?

lukas.lebo · May 11, 2017, 03:23

Hi

I'm currently doing a mesh-study to prove grid independency for a case of turbulent flow around a cube.

It is extremely hard to reach small yPlus and I can only do it with an O-Grid to stay at reasonable cell count. The problem with the O-Grid is it is very unstable at the edges and corners.

The simulation will only run if I do multiple inner Loops. If I set nOuterCorrectors to 50 it takes 15 loops to converge (pressure residual criterion is 10^-7). But I tried 5 nOuterCorrectors and the simulation is still able to run. Maybe I could reduce it further, but haven't tested it yet.

Is it bad practice to do multiple inner loops if you are interested in the velocity and pressure fluctuations at the object? I'm afraid it could dampen the fluctuations?

Thank you!

Lukas

Picture of the O-Grid: http://imgur.com/a/yfPUo

Gang Wang · February 27, 2020, 09:47

Hi!

I also did the similar topics with you, have you got the answer to this?

Best,
Gang

May 11, 2017, 03:23	LES and pimpleFoam: Is it wrong to do many Pimple/inner Loops?	#1
lukas.lebo New Member Lukas Lebovitz Join Date: Mar 2017 Location: Zürich, Switzerland Posts: 25 Rep Power: 9	Hi I'm currently doing a mesh-study to prove grid independency for a case of turbulent flow around a cube. It is extremely hard to reach small yPlus and I can only do it with an O-Grid to stay at reasonable cell count. The problem with the O-Grid is it is very unstable at the edges and corners. The simulation will only run if I do multiple inner Loops. If I set nOuterCorrectors to 50 it takes 15 loops to converge (pressure residual criterion is 10^-7). But I tried 5 nOuterCorrectors and the simulation is still able to run. Maybe I could reduce it further, but haven't tested it yet. Is it bad practice to do multiple inner loops if you are interested in the velocity and pressure fluctuations at the object? I'm afraid it could dampen the fluctuations? Thank you! Lukas Picture of the O-Grid: http://imgur.com/a/yfPUo Last edited by lukas.lebo; May 11, 2017 at 05:20.

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February 27, 2020, 09:47		#2
Gang Wang Member Gang Wang Join Date: Oct 2019 Location: China Posts: 64 Rep Power: 8	Hi! I also did the similar topics with you, have you got the answer to this? Best, Gang